diff --git a/dbtmetabase/format.py b/dbtmetabase/format.py
index 862a715..2be2994 100644
--- a/dbtmetabase/format.py
+++ b/dbtmetabase/format.py
@@ -28,8 +28,8 @@ def __init__(
         self.include = self._norm_arg(include)
         self.exclude = self._norm_arg(exclude)
 
-    def match(self, item: str) -> bool:
-        item = self._norm_item(item)
+    def match(self, item: Optional[str]) -> bool:
+        item = self._norm_item(item) if item else ""
 
         for exclude in self.exclude:
             if fnmatch.fnmatch(item, exclude):
diff --git a/dbtmetabase/manifest.py b/dbtmetabase/manifest.py
index a48348c..88d82b8 100644
--- a/dbtmetabase/manifest.py
+++ b/dbtmetabase/manifest.py
@@ -42,7 +42,8 @@
     "caveats",
 ]
 
-# Default model schema (only schema in BigQuery)
+# Default values for non-standard sources
+DEFAULT_DATABASE = ""
 DEFAULT_SCHEMA = "PUBLIC"
 
 # Foreign key constraint: "schema.model (column)" / "model (column)"
@@ -411,7 +412,13 @@ def ref(self) -> Optional[str]:
 
     @property
     def alias_path(self) -> str:
-        return ".".join([self.database, self.schema or DEFAULT_SCHEMA, self.alias])
+        return ".".join(
+            [
+                self.database or DEFAULT_DATABASE,
+                self.schema or DEFAULT_SCHEMA,
+                self.alias,
+            ]
+        )
 
     def format_description(
         self,